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73 
157 
1921 


OPTO      L  C  T  I  O  N  S 
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INSTRUCTIONS 
FOR    OPERATING 

T/je  Universal 
Ophthalmometer 


OPTOMETRY 


Copyright  1921 

by  the 

General  Optical  Co.,  Inc. 

Mount  Vernon,  N.  Y. 


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7  'he  Unive?  'sal  Ophthab/i offi cte? ' 


LOCATING    FIRST    PRINCIPAL     MERIDIAN     (FIGURE    a) 


THE  Universal  Ophthalmometer  is  an  instru- 
ment of   precision   and   its   principle   is   optic- 
ally   correct.       Unless    the    operator    handles 
the  instrument  properly,  much  of  its  value  will  be 

lost. 


Remember  that  the  Universal  is  a  carefully  con- 
structed instrument,  and  with  ordinary  care  will 
last  indefinitely.  Handle  the  instrument  freely  and 
smoothh',  but  never  attempt  to  force  or  jerk  it  into 
position. 

The  manipulation  of  the  instrument  is  simple. 
Observe  the  following  rules  and  >ou  will  have  no 
difficulty  in  obtaining  the  accurate  results  made  pos- 
sible by  the  Universal  Ophthalmometer.  Be  sure 
the  ophthalmometer  has  a  substantial  support,  one 
that  may  be  quickly  and  smoothly  raised  or  lowered. 
This  is  important,  as  the  accuracy  and  speed  to  be 
gained  in  using  the  Universal  may  be  offset  by  a 
make-shift  support. 

First: — Switch  on  lights  by  turning  switch  (part 
10)  on  base  of  instrument.  If  you  wait  until  after 
the  patient  is  properly  seated  to  turn  on  the  light, 
the  noise  of  the  snap  switch  and  sudden  flash  of 
light  in  the  mire  boxes  may  startle  her  and  cause 
her  to  move  out  of  position. 


DOCTOR     GUIIIING     PATIENT'S     HEAP     INTO     POSITION 
(EICUUE     b) 


Second: — Then  look  into  the  adjustable  eyepiece 
(part  11)  and  turn  it  until  cross  lines  appear  sharp 
and  distinct.    (See  figures  D  and  E.) 

A  good  way  to  focus  hair  lines  is  to  hold  a  piece  of 
white  paper  before  end  of  telescope  while  turning 
eye  piece.  This  will  make  the  hair  lines  stand  out 
clearly  and  distinctly.      (See  figure  F.) 

Third: — Adjust  the  oiihthalmometer  table  so  that 
with  arms  folded  in  a  natural  position  on  table  top, 


PATIENT  S    EYE    ON     LEVEL     WITH     DOT 
(FIGURE     C> 


PAGE       THREE 


CROSS    IIATRS    OUT    OK    FOCUS 
(FIGURE    Ii) 


the  forehead  and  chin  of  patient  are  comfortably  but 
firmly  placed  well  into  the  head  and  chin  rests.  (See 
figure  A.)  When  patient  places  forehead  against 
head  rest  (part  2),  instruct  her  to  raise  eyebrows. 
In  this  way,  the  cornea  is  fully  exposed  and  eyebrows 
do  not  interfere  with  the  images.  It  is  well  not  to 
depend  on  patient  properly  placing  her  head  in  rests. 
The  operator  or  the  nurse  should  guide  patient's 
head  into  the  proper  position.    (See  figure  B.) 

Fourth: — Raise  or  lower  chin  rest  (part  1)  by  turn- 
ing small  adjusting  screw  (part  13)  at  operator's 
end  of  instrument,  so  that  face  is  in  an  upright  posi- 
tion and  outer  canthus  of  eye  is  in  line  with  white 
spot  (part  4)  on  inside  of  head  rest.  This  will 
bring  the  horizontal  meridian  of  the  eye  in  line 
with  the  horizontal  position  of  the  instrument  when 
adjusted.    (See  figure  C.) 


CROSS     HAIRS     IN     FOCUS 
(FIGURE    E) 


V  A  G  E       FOUR 


FOCUSING    THE     HAIR    LINES 
(FIGURE    F) 


Fifth: — Turn  dial  so  that  both  sight  holes  (part 
14-14)  are  in  horizontal  position.  This  will  bring 
the  figure  45  on  the  large  dial  to  the  top  of  the 
instrument.  Then  raise  or  lower  instrument  until 
white  spot  (part  4)  at  side  of  head  rest  is  visible 
through  the  sight  hole  ,  in  dial.  [This  is  done  by 
turiung  large  adjusting  screw  (part  12)  at  oper- 
ator's end  of  instrument.  See  operator's  left  hand 
in  figure  C]      [Be  sure  locking  handle  (part  9)  is 


[MAGES    CENTERED    ON    CROSS    HAIRS 
(FIGURE    G) 


PAGE       FIVE 


LOCKINC.     THE     INSTKUMENT 
(FICUUK     II  ) 


loose.]  Swing  blinder  (part  3),  attached  to  head 
rest,  so  that  it  covers  patient's  left  eye.  Then  swing 
telescope  until  patient's  right  eye  is  in  position  di- 
rectly before  it.  Instruct  patient  to  look  into  tele- 
scope for  the  rellection  of  her  own  eye,  and  to  look 
steadily  at  it  . 

SixtJi: — Operator  then  adjusts  telescope  by  raising 
or  lowering  or  turning  from  side  to  side  until  images 
of  mires  are  located  and  central  images  are  centered 
on  cross  hairs.  (See  figure  G.)  Disregard  the  two 
outer  images. 

Scvcntli: — Then  lock  telescope  by  pulling  toward 
the  operator  the  locking  handle  (part  Q)  on  right 
side  of  upright.      (See  figure  H.) 


mires   just   touching 
(figure  j) 


P  A  G  E        SIX 


LOCATING     SECOND     PRINCIPAL      MERIDIAN 
( FIGURE     k) 


Eighth: — Now  turn  focusing  wheel  (part  8)  on  side 
of  telescope  until  images  are  focused  clearly  and 
distinctly. 

Ninth: — Locate  the  first  principal  meridian  by  tak- 
ing hold  of  the  rough  grip  section  (part  7)  and 
revolving  the  telescope  until  the  black  lines  running 
through  the  center  of  each  mire  are  in  a  straight  line, 
as  in  figures  J,  L  or  M. 

Tenth: — Grasp  one  of  the  convenient  pegs  (part 
6)  on  the  disc  (see  operator's  left  hand  in  figure 
A)  and  turn  disc  either  way  until  the  inner  edge 
of  step  mire  just  touches  the  inner  edge  of  the  oblong 
mire.      (  See  figure  J.) 

The  white  double  pointer   (part   lb)   now  registers 


mires  separated 
(figure  l) 


MIRES    OVERLAPPED 
(FIGURE     M) 


P  A  G  E       S   E  \'  E   X 


the  first  principal  meridian  on  the  small  dial  and 
its  dioptric  value  on  large  dial.  Write  down  this 
finding.     For  example : 

45.  D.  in  meridian  0° 

Eleventh: — Locate  second  principal  meridian  by  re- 
volving telescope  until  black  lines  running  through 
the  center  of  each  image  are  again  in  a  straight  line. 
Again  grasp  one  of  the  convenient  pegs  and  turn 
disc  either  way  until  inner  edge  of  step  mire  again 
just  touches  inner  edge  of  oblong  mire.  The  white 
double  pointer  (part  16)  now  registers  the  second 
principal  meridian  on  small  dial  and  its  dioptric 
value  on  large  dial.  Write  down  this  finding.  For 
example : 

47.  D.  in  meridian  90° 

^  ou  have  now  located  the  two  principal  meridians 
and  their  dioptric  values  represented  by  the  follow- 
ing diagram: 


90 


0 


45.  D 


A7.  D 


To  avoid  confusion,  figure  from  here  on  from  this 
diagram  instead  of  from  the  dials  of  the  ophthal- 
mometer. 


FACE       K  I   C,  II   T 


Twelfth: — If  you  use  minus  cylinders  the  power  of 
the  minus  cylinder  will  be  the  difference  between 
the  two  dioptric  values  on  the  diagram  and  the  axis 
will  be  the  meridian  associated  with  the  lower  di- 
optric value.     In  the  abo\e  example  — 2.00  axis  0°. 

If  you  use  plus  cylinders  the  power  of  the  plus  cyl- 
inder will  be  the  difference  between  the  two  dioptric 
values  on  the  diagram  and  the  axis  will  be  the 
meridian  associated  with  the  higher  dioptric  value. 
In  the  above  example  4-  2.00  axis  90°. 

Repeat  above  operations  when  examining  the  left 
eye. 

Bear  in  mind  that  the  ophthalmometer  findings  indi- 
cate the  exact  cylinder  that  would  correct  the  corneal 
astigmia  if  the  lens  could  be  placed  on  the  cornea. 
Rut,  inasmuch  as  the  correcting  lens,  in  order  to 
clear  the  lashes,  must  be  set  away  from  the  cornea, 
its  power  must  naturally  be  changed  to  produce  a 
similar  effect. 

However,  the  cylinder  indicated  by  the  ophthalmo- 
meter affords  the  proper  basis  from  which  to  start 
all  other  tests,  subjective  or  objective. 


ly^e  Green  a  fid  Red  Markers 

The  green  and  red  markers  (parts  17  and  15)  are 
purely  auxiliary  and  confusing  to  most,  but  some 
operators  who  do  not  write  down  their  findings  use 
the  green  marker  to  mark  the  first  principal  meri- 
dian and  the  red  to  mark  its  dioptric  value. 


PAGE      NINE 


Form  B~5 


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